The present invention relates to the technical field of a digital image processing apparatus for use with digital photoprinters and like machines that read the image on a film photoelectrically and output a print (photograph) having the image reproduced thereon.
Most of the image recorded on photographic films such as negatives and reversals (which are hereinafter referred to as “films”) are conventionally printed onto light-sensitive materials (photographic papers) by a technique generally called “direct exposure” (analog exposure) in which the image on a film is projected onto the light-sensitive material for areal exposure.
A printer that adopts digital exposure has recently been commercialized. In this “digital photoprinter”, the image recorded on a film is read photoelectrically and converted into digital signals, which are subjected to various kinds of image processing to produce recording image data; a light-sensitive material is exposed by scanning with recording light modulated in accordance with the image data, thereby recording a (latent) image which is then processed photographically to produce a print.
In digital photoprinters, the image is converted to digital image data and exposing conditions can be determined by processing that image data. Hence, by using such digital photoprinters, the correction of dropouts or blocked-ups due to photography with rear light or an electronic flash, the correction of color or density failures, the correction of under- or over-exposure, the correction for the insufficiency of marginal light, sharpening, the compression/expansion of the dynamic range of densities (imparting the dodging effect by processing of the image data) and various other kinds of image processing that have heretofore been impossible or difficult to accomplish by the direct exposure technique can be performed with high degrees of freedom to produce prints of much better quality. In addition, a plurality of images can be composited into a single image or one image can be split into segments or even characters can be composited by the processing of image data. If desired, prints can be outputted after desired editing/processing in accordance with a specific application.
The capability of digital photoprinters is by no means limited to outputting the image as a print (photograph) and they enable the image data to be supplied to computers or stored in recording media such as floppy disks; thus, with digital photoprinters, the image data can be used in various applications other than photography.
Having these features, the digital photoprinter is composed of the following three basic parts: a scanner (image reading apparatus) that reads the image on a film photoelectrically; an image processing apparatus that performs image processing of the read image to determine the exposing conditions for image recording; and a printer (image recording apparatus) that scan exposes a light-sensitive material in accordance with the determined exposing conditions and performs development and other necessary processes to produce a print.
In the scanner, the reading light issuing from a light source is allowed to be incident on the film, thereby producing projected light that carries the image recorded on the film; the projected light is then passed through an imaging lens to be focused on an image sensor such as a CCD sensor which performs photoelectric conversion to read the image, which is optionally subjected to various kinds of data processing before it is sent to the image processing apparatus as the image data (image data signals) from the film.
In the image processing apparatus, the image processing conditions are set on the basis of the image data that has been read with the scanner and image processing is applied to the image data in accordance with the thus set conditions, thereby producing output image data for image recording (i.e., exposing conditions) that are subsequently sent to the printer.
In the printer, if it is an apparatus that adopts exposure by scanning with optical beams, the beams are modulated in accordance with the image data supplied from the image processing apparatus and as said optical beams are deflected in a main scanning direction, the light-sensitive material is transported in an auxiliary scanning direction perpendicular to the main scanning direction, whereby the light-sensitive material is exposed to the image-carrying optical beams to form a latent image; the exposed light-sensitive material is then developed and otherwise processed in accordance with its type so as to produce a finished print (photograph) reproducing the image that has been recorded on the film.
As mentioned above, the image processing apparatus in a digital photoprinter sets the image processing conditions in accordance with the image data that has been read with the scanner and the image data is processed under the thus set image processing conditions to produce the output image data. This enables sharpening, dodging, color/gradation correction and various other kinds of image processing to be performed with a very high degree of freedom.
When performing these kinds of image processing, information about the principal part of the image is effective for setting the appropriate image processing conditions and producing an image of high quality.
The information about the principal part of an image is also important in the conventional photoprinter relying upon direct exposure. Users who receive the final print are satisfied to some extent if the principal part of the image (which is in most cases the face of a person) has appropriate levels of color and density; therefore, in direct-exposure photoprinters, the exposing conditions are so set that the principal part of the image will be finished appropriately to ensure consistent outputting of appropriate prints. However, direct-exposure photoprinters can adjust only the color and density of the image and no further adjustments of the image are possible.
Finishing the color and density of the principal part of the image is also important in digital photographers, however, in addition thereto for the digital photographers, an image processing availing the high degree of freedom of digital photoprinting was being expected strongly, as digital photographers enable the processing of an image (its adjustment) to be performed at a considerably higher degree of freedom than direct exposing photoprinters and hence, the information about the principal part of the image can be utilized more effectively, as mentioned already. However, conventional digital photoprinters were unable to comply fully with the expectation.
For example, it may be possible to produce high quality image prints satisfactory to users by conducting the image processing's in a manner suited best for the contents of image scenes (such as figure or scenery photographs). However, for accomplishing such image processing, it is necessary to interrupt the continues work for obtaining image processing conditions suitable for respective image for imputing image scenes, and to set up again image processing conditions suited best for the imputing image scenes, and so the processing results in a problem of extremely lowered productivity.